def judge_event_type(event_type):
    def crn(bot):
        def util(cmd, alias=[]):
            cmds = [cmd] + alias
            def register_function(func):
                bot.cmd_route[event_type].append([cmds, func])
            return register_function
        return util
    return crn

on_command = judge_event_type('command')
on_request = judge_event_type('request')
on_notice = judge_event_type('notice')
